In connection with navigation devices (including route planners), the term “points of interest”, or POIs in short, refers to locations that are of particular interest to a user because of service offerings, tourist attractions or leisure offerings. For example, filling stations, pharmacies, cash dispensers, vehicle repair shops, accommodation, museums, cinemas or other tourist attractions can be identified as POIs. POIs can be indicated visually (for example, in the form of symbols or POI lists) or acoustically by a navigation device.
The search for POIs by a navigation device usually begins with the user specifying a POI class (e.g. filling station) in the course of inputting a destination. Then, on the basis of cartographic data and the current position, the navigation device identifies all POIs of the predetermined POI class within a predetermined search radius. The search radius in this case can be preset in the navigation device or can be predetermined by the user.
A method for inputting a destination on a navigation device is known from EP 1 269 119 B1, wherein a user is provided with a destination name list for selection of a destination, a distance criterion being used for compilation of the list. For this purpose, all previously stored destination names that lie within a predefined search radius, or within a search radius predetermined by the user, are retrieved from a memory and made available to the user, in the form of a destination name list.
A method of searching for POIs on the basis of a predetermined search radius can be disadvantageous, since the search time, which is proportional to the number of POIs that are processed within the predetermined search radius, is not predictable. Thus, for example, in the case of a search radius in a densely populated region (for example, in metropolitan areas), a POI search can result in a large number of POI hits, with the result that, on the one hand, the search time is greatly increased and, on the other hand, the search result cannot be indicated in a clear manner. In particular, processing and indication of a large number of POI hits place unnecessary demands on resources of the navigation device that would otherwise be available for other operations. This problem can be rectified, for example, if the search radius in each case is adapted to the conditions of a search location. Specifying a suitable search radius is difficult, however, since the user does not know in advance how many POIs are located within the predetermined search radius.